This application claims the priority of German patent document 10 2005 043 702.8-13, filed Sep. 14, 2006, the disclosure of which is expressly incorporated by reference herein.
The present invention is directed to a method for measuring and displaying an engine oil filling level in a vehicle.
Previously known evaluation methods for engine oil filling level monitoring systems utilize filling level switches or filling level sensors which are usually implemented as corresponding software and hardware components in the vehicle. In such methods, rigid state times are used; that is, individual time components are summed rigidly in real time in order to determine how long the determined engine oil filling level is present, and the summed duration is compared with respective time limiting values. Parameters (such as, for example, vehicle speed) which influence the engine oil filling level have hitherto been used in the evaluation methods for gating out the signals of the engine oil level monitoring systems in specific speed ranges, i.e., in order to interrupt or abort the summing of the state time, to influence the time limiting values, or to influence the measured value of the engine oil filling level, for example by correcting the temperature or rotational speed.
German patent document DE 100 44 916 A1 describes a method for measuring and displaying the oil level in a motor vehicle, which uses an oil level sensor, and the measured values are averaged over a relatively long distance. In addition, the measured value which is supplied by the oil level sensor for the oil level display or oil level warning is corrected by another measured parameter which influences the measured value. The parameters are preferably the engine speed and the oil temperature.
German patent document DE 196 02 599 C2 discloses another method for determining the amount of fluid (in particular, engine oil) in a motor vehicle. The method acquires variables which are indicative of the driving state in the driving mode, determines the instantaneous driving state therefrom, continuously acquires the instantaneous value of the filling level by means of a filling level sensor at least during selected driving states, and determines the instantaneous filling quantity from said value by means of a predefined dependence of the quantity of fluid on the driving state and on the filling level. The acquired variables which are indicative of the driving state include at least the speed of the vehicle and the engine speed. The filling quantity is determined separately for a plurality of driving states with different speeds of the vehicle and engine speeds, and the quantity of engine oil is determined taking into account a consumption quantity proportion which is determined by means of a predefined consumption quantity proportion/engine oil dependence.
One object of the present invention is to provide a method and apparatus for measuring and displaying an engine oil filling level in a vehicle, which permit improved display quality of a determined engine oil filling level in all the driving states.
This and other objects and advantages are achieved by the method and apparatus according to the invention, which determines the magnitude or length of individual time components as a function of driving-state-dependent parameters. The determined individual time components are then summed to determine the duration of a particular engine oil filling level to form a state duration. The latter is then compared with predetermined time limiting values of the respective state of the engine oil filling level.
The method according to the invention can thus use, for example, rigid time limiting values. For example, an oil level warning can be issued if the engine oil filling level lies below a predefined filling level limiting value for longer than the predetermined time limiting value, for example 60 s. The individual time components of the state duration are, however, determined as input variables as a function of parameters. That is, the magnitude or length of the individual summed time components in which a specific engine oil filling level is present are dependent on the driving state.
The inventive determination of the state duration as a function of driving-state-dependent parameters permits the display quality of a determined engine oil filling level to be improved or enhanced in all driving states in the engine operating mode, i.e., reliable, stable and precise detection of the current engine oil filling level is made possible. In addition, as a result of the method according to the invention with variable state time components, cost-effective oil level switches are used and the display quality is nevertheless enhanced. Driving trials have shown that a significant increase in the display quality can already be achieved solely by using speed-dependent state time components.
In one refinement of the method according to the invention, the driving-state-dependent parameters are calculated as weighting factors. In order to determine the magnitude or length of the respective time component, the weighting factors are multiplied by a real time value determined for the respective time component. If the state duration is determined as an input variable (for example, as a function of the speed of the vehicle), an individual state time component with a predefined factor is calculated, for example, for each real time component if the engine oil filling level lies below the filling level limiting value at a determined current speed. The sum of the time components that are collected in this manner is formed and compared with the respective time limiting values.
The driving-state-dependent parameters comprise, for example, the speed of the vehicle, engine speed, engine oil temperature, engine load moment, engine torque, longitudinal acceleration, lateral acceleration or pedal value.
In one refinement of the method according to the invention, the driving-state-dependent parameters are stored as continuous or noncontinuous functions in a memory. That is, for each parameter value there is a factor by which the real time component is multiplied in order to determine the state time component.
In a further refinement of the method according to the invention, the time components are adapted continuously by means of the driving-state-dependent parameters.
The device according to the invention for measuring and displaying the engine oil filling level in a vehicle includes a filling level switch or a filling level sensor and an evaluation and control unit which sums measured values of the filling level switch or sensor, to determine the duration of a respective state of the engine oil filling level in the form of determined time components to form a state duration, and compares it with predefined time limiting values of the respective state of the engine oil filling level. In order to determine driving-state-dependent parameters, the evaluation and control unit acquires information from at least one vehicle system and evaluates it in order to determine the magnitude or length of the individual time components as a function of the determined driving-state-dependent parameters.
The method and apparatus according to the invention permit simple and cost-effective evaluation while simultaneously improving the display quality of the engine oil filling level.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.